Spirally wound paper tube



July 13, 1965 w. A. BIGGS, JR., ETAL 3,

SPIRALLY WOUND PAPER TUBE Filed Jan. 15, 1963 2 Sheets-Sheet 1INVENTORS: WILLiAM A. B|6G ,J\2and C$ERLES K. buNLAP, J12.

United States Patent 3,194,275 SPIRALLY WQUND PAPER TUBE William A.Iiiggs, .112, and Charles K. Dunlap, In, Hartsville, 5.0, assignors toSonoeo Products {lump-any, Hartsville, S. C., a corporation of SouthQarolina Filed Jan. 15, 1963, Ser. No. 251,614 3 Claims. (Cl. 138-144)This invention relates to paper tubes and more particularly to aspirally wound paper tube for the winding of sheet material such astextile material and the like.

It is a common practice today to utilize wound, multiply paper tubes ascarriers or cores for sheet material such as paper, cloth, carpetmaterial and the like. Such tubes or cores used for the winding of heavysheet material such as carpet material are required to be of highstrength to resist crushing and buckling when subjected to the forcesgenerally encountered when wound with such carpet material and the like.Carpet material is generally wound in long lengths on its tubularcarrier producing a very heavy load and although the spiral tube of theinvention may be used for the winding of any material where a strongcarrier is desired, it is particularly useful for the winding of suchheavy carpet material.

Paper tubes in use today as a carrier for long lengths of carpetmaterial are required to have both a high resistance to radial crushingand a high beam strength which, as is well known, is measured by theability of the tube to withstand a centrally positioned load with thetube supported only at its ends. Such present day tubes or cores aregenerally made by convolutely winding a paper web into a tube as aconvolutely wound tube has by its nature a beam strength greatly inexcess of a spirally wound tube together with a satisfactory degree ofcrush strength. Furthermore, the convolute tube when subjected to a beamload fails by a buckling or pleating of its walls whereas the spiraltube fails by splitting along its spiral tube seam or what is known asseam splitting. Such seam splitting is highly undesirable in that itpinches the material wound on the core with resulting damage to thematerial.

Primarily because of its lower cost of production, there has been acontinuous search for a spiral tube which will provide the beam andcrush strength of the convolutely wound tube for use in such areas ofuse as described above. While spirally wound tubes have been well knownfrom the earliest times, a suitable spiral tube'for such a use has notheretofore been obtained. In addition to the high radial crushingstrength of spiral tubes in comparison with convolute tubes, theiruniform concentricity and radial dimensional stability, the lowproduction costs common to the spiral tube has intensified the searchall to no avail. Some progress has been made in increasing the beamstrength of such spiral tubes by increasing the Wall thickness of thetube and with the use of stronger paper but the resulting tubes stillhave far less than the desired strength and the slight strength increaseobtained is offset by the high cost and increased bulkiness of thetubes.

Accordingly, a primary object of this invention is to provide a new andnovel spiral tube having a high beam strength and high crush strength.

Another object of this invention is to provide a new and novel spiraltube for use as a core or carrier for heavy sheet material such ascarpet material and the like.

A further object of this invention is to provide a new and novel spiraltube for use as a core for heavy sheet material which tube has a beamstrength and crush strength substantially the same as a correspondingconvolutely wound tube and which fails by buckling rather than by seamsplitting soas to avoid damage to the material wound on the tube.

Still another object of this invention is to provide a Patented July 13,19%5 new and novel spiral tube having a high degree of dimensionalstability so as to remain substantially constant in length throughoutchanges in moisture content.

This invention further contemplates the provision of a new and novelspiral tube wound at a winding angle not heretofore considered possiblewhich is characterized by a beam strength and crush strengthsubstantially equivalent to that of a corresponding convolutely woundtube, which utilizes spiral tube winding equipment presently availableand which may be manufactured from readily available inexpensivematerials at a relatively low production cost.

Other objects and advantages of the invention will become apparent fromthe following description taken in connection with the accompanyingdrawings.

In general, the objects of the invention and related objects areaccomplished by providing a plurality of strips of paper which arespirally wound in overlapping relationship with adhesive therebetween toform a spiral tube. The paper strips which contain fibers common topaper have the fibers extending lengthwise in the direction of thelongitudinal axis of the paper strips or what is generally referred toas the paper machine direction. The winding angle of the paper strips iswithin the range of between 15 to 27 degrees and preferably an angle ofapproximately 17 degrees so that the long axis of the strips andconsequently the fibers in the strips approach closely a parallelrelationship with the axis of the tube to provide a tube of high beamstrength and high crush strength together with ahigh degree ofdimensional stability.

The novel features which are believed to be characteristic of theinvention are set forth with particularity in the appended claims. Theinvention itself, however, both as to its organization and method ofoperation may be best understood by reference to the followingdescription taken in conjunction with the accompanying drawings inwhich:

FIGURE 1 is a plan view of a spiral tube winding apparatus illustratingthe winding of the tube of the invention;

FIGURE 2 is a side view of a tube constructed in accordance with theinvention;

FIGURE 3 is a graph illustrating the relationship between tube beam andcrush strength and tube winding angle;

FIGURE 4 is a graph illustrating the relationship between the ratio oftube beam and crush strength with tube winding angle; and

FIGURE 5 is a graph illustrating the relationship between tube lengthchange under varying moisture conditions with tube winding angle.

Referring now to the drawings and to FIGURES 1, 2 in particular, thereis shown in FIGURE 2 a spiral tube designated generally by the letter Twhich is constructed in accordance with the invention. The spiral tube Tis wound on slightly modified conventional spiral tube winding apparatusportions of which are shown in FIGURE 1. The apparatus of FIGURE 1includes a frame designated generally by the numeral 11 arranged tosupport a winding mandrel 12 around which a continuous belt 13 is loopedin the conventional manner for advancing the tube T in the direction ofthe arrow P. The belt 13 is mounted in the conventional manner on drumsor pulleys 14, 16 at least one of which is rotatableby suitable drivingmeans and the pulleys 14, 16 are arranged for adjustable slidingmovement on a frame 17 positioned for angular adjust ment on a base 18.The spacing between the drums 14, 16 is adjusted by means of threadedshafts 19, 20 arranged to be manually rotated by means of hand wheels21, 22 respectively for belt tensioning purposes.

The spiral tube T of the invention is wound from a pinrality of plies orstrips of paper containing fibers common to paper and, in the specificembodiment illustrated, the

glue from the strips'as shown in FIGURE -1.

' not applied to the intermediate strip 28 and it is broughtv belt 13asshown.

. paper strips are seven in number including an inner strip a '23;intermediate strips 24,;25, 26, 27, 28.and outer strip area-275 '29.The'paperstrips 23 through 29 are formed in a conventional manner on apapermaking machine but, all of the; strips employed in the constructionoftthe tube T of the, invention are made by the ;Well-knownvtechnique ofthe arrows I. In" other words, the paper strips 23 to 29 have theirlongitudinal axis parallel to what is referredto as the paper makingmachine direction. This is accomplished by cutting thepaper web parallelto the 7 direction the web travels during its formation on'the papermachine to form the strips 23-29." o

'Inthe manufacture of spiral tubes under present day practice, the,winding angle, 'identified in FIGURES 'JI, 2

as X"; is generally'withingthe range of 50 to 80 degrees and as has beenexplained tubes made at a winding angle within this range do not havethe desired beam strength. In'accordance with the inventiomthe windingangle X- at which the strips 23fto 29"are wound on the winding mandrel12 iss within the range of 15 to 27 degreespreferably within 'therangeiof ,17 to 22 degrees. In tthe specific embodiment illustrated, thewinding anlge X;j is

' wherein-the fibers of thestrips lie'substantiallyoparallel a with thelongitudinal axis'of'r the strips or in: the'idirectio'n Theresults-shown in Table'Iwere obtained byfwinding multi-ply'spiral' tubeshaving a3" inner. diameter, and a 0.150? wallthickness at iwindingangles-ranging frornamaximum of 37 /4" to aminimu'nr (Jil n/l3. Thepaper strip widths, of course, vary in accordance with the windingangle. The physical limitationsgOfthe spiral tube V winding machinewould not pfi rriitfthe winding anglei to V a be reduced'belowapproximately ISdegrees as at this point 1' the length of. the windingbelt and the spacing of the belt} drums for winding a tubeatthis'winding angle becam e prohibitively large in addition to thebeamstrengthttest as described above, ,a crush strength test was conducted I on specimens of these various tubes both; of which tests",

are considered in the-industry as standard. As is'welhj known, thecrush'strength'test is carriedout by loading a standard 3'v'j1ength offtub'e;betweenflat platens until failure. o a

strength ratio as shown in'the graph of FIGURE 4- and as will beexplained hereinafter.-

As shown in FIGURE 1,;the inner paper strip 235 which formsthe inner plyof the tube is wound on the mandrel,-

thereto by a suitable lubricatingv device. 31.: Paper strips 24 through27 whichv are :preferably Wound onto the;

mandrel fr oin'theside opposite the inner strip 23 as shown which isprovided with scrapers'33i for removing excess in dry over a set ofguide rolls 34.

vancediover a glue applicator 36'. Strip 29 is then vwound Glue istogether with theother strips on the mandrel below the which not onlyaid in compressing the wound paper strips together for increasedadherence but additionally serve; to prevent the mandrel 12 from movingout. of, alignment as a result of thewinding forces exerted'by the belt13 on the mandrel.

a 7 Suitable support rollers 37 are pro-" 7 vided on the spiral tubewinder as shown in FIGURE; 1'

' wound tube thereby avoiding.thefpossibilityof injury to 7 materialwound Ion'the' tube. ,Thisis considered to bee tive tothe longitudinalaxis of the tube as shown in FIG- URE 2.- V a a The novel resultsaccomplished with the spiral tube" ofthe invention are shown clearly inFIGURES 3-5 and in Table I belo'wz' t TABLE 'I Beam. Paper Strip WidthWinding Crush Beam i Strength] (inches) Angle Strength Strength Crush t(degrees) (lbs;) ribs.) Strength I V V Ratio.

37 79 r 281 3. a? 79 u 310 3.93 29 73 V 325 4.45 25% 64 Y 349 5A5. 21%69 382 5.54 17% 70 400 5. 70'

The results of the beam strengthi and lcrushl-te'sts are :7 tabulatedinTable '1 and are plotted on theg'raphtshown" FIGURE 3f: It will be notedthat' throughoutgthef o winding anglelrange of. approximatelyV37,'to"17' degreesi V t there-Was a 431%, increase"in=beainfstrength;with an ack- V companying crush strengthidecrease with;onlyi'about 12%;: o

A ratio:of beamstrength to crush strength'wasutilized as representativeof both of, theidesirable.strengthiactors;-

' in a tube lofthe inventioh .andFIGURE4 shows the"yari ous ratiosplotted on a graphi IAsiexplaine d'abov, the; last beamystrength tocrushstrength ratio obtained was t at the ,17 degreeangle':approximately as itheaphysicallimitationsfof the ,spiraltubewinding; machine militates against the winding of sp'iraltub'es to anytsubstantial 'de f gree below this winding angle. 1 Poin'ts'Afand Bplotted at the zero winding angleiposition'offltthegraphof FIG- UREA arestrength-ratio figures for twoconvolutely-w wound tubes of the samediameter and wall thicknesston which the same testswere run and thestrength ratios ob-' tained can be'considered tolbe those correspondingma 1 theoretical-spiral'tube havinga zero degree winding angle. a

Iti'will be no tedxthat throughout the winding-angle range .ofapproximately '17 to -27fidegrees the vgbeani't l' strength/crushstrength ratio 'was' s ubstan'tially the same 1 and approachessubs'tantially that of'the convoluteftube': samples A'and B.Z The beamstrength/crush strength ratio droppedoft sharply above a. winding anglefcrap;

prox mately 27. degrees and has 'beenzexplained above; a I winding anglebelow approximately 17 degrees couldjno t for all practical purposes'bemeasured. jIt will also be; noted that the beamjstrength/crush'stren'gth ratio' of the tubes appeared to beat a r'naxirnumiat awindingangleof "between l7 and 22 degrees i i In additionto the atthe lowwinding angles of the tubespf the invention,

it wasno ted that the seam splitting upon failure common to spirallyWound tubes subjected tofa beam test didnot oc- C111.i)ill2 rather'thatthe. tube buckled asin the convolutely completely new and unexpectedresult and considerably enhances the commercial'app'eal of the tubes VThe novel resultsoftthe inventionarebelieved to :be. i obtained as aresult of the close app'roachoftheffibers'in the paperostrips' used towind the tube Tto a parallel relationship with the longitudinaliaxis 0fthetube-T. 'As' a result of this positioning of the fibers ofthestripsforming the tube, a highfresistance is offered to collapse of the tubeunder a beamload such as thetbearn strength 'of t V a convolutely woundtube which is wound with'the fibers extending transversely of, the crossgwound papershe'et on; in other-words; parallel to' the=longitudinalaxis of the: convolute tube. The'tube T io f the invention can be 'saidto have strength characteristics closely app'roximatg ing those. of aconvolutelywvoundtube. t

Other new and unexpected Tresults developed when: V spirally 'woundlpaper tubes wound. atjldw winding angles I high strengthcharacteristics obtained.

in accordance with the invention were subjected to dimensional stabilitytests. In conducting one such dimensional stability test on the tubes ofthe invention, six spiral tubes having an inner diameter of 3", a 0.150"wall thickness and a length of 30" were wound at winding angles of 3616;3155; 2854; 2536; 2149; and 1716 using seven plies of paper. In thetest, the moisture content of these tubes was changed from 6% to 25% asthe change in tube length resulting from this moisture content changewas measured.

The resulting percent changes in length of these tubes are plotted onthe graph of FIGURE 5 and it will be noted that the percent change intube length varies from a figure of 0.82 at the higher tube windingangle of 37 16' to a percent change in length figure of 0.47 at thelower winding angle of 1716. Here again as in the beam strength/ crushstrength ratio graph the reduction in the percent change in tube lengthbecomes increasingly small as the tube winding angle falls within the 15to 27 degree range so that,

' as shown in FIGURE 5, a curve drawn through the plotted pointsindicates a gradual decrease in curve slope at these lower tube windingangles.

Point C in the graph of FIGURE 5 indicates the percent change in lengthunder the same moisture content change specified above in a spirallywound tube having an inner diameter of 3%, an outer diameter of 4" and alength of 30" but wound at a winding angle of 59 degrees. It will benoted that the length change with moisture content change at the higherwinding angle far eX- ceeds that of the winding angle range of theinvention. The graph of FIGURE 5 thus reveals clearly that a substantialincrease in dimensional stability is obtained at the lower angles ofwind and the maximum dimensional stability is obtained within the rangeof winding angles comprising the invention.

It can be seen with the novel construction of this invention that amulti-ply spirally wound paper tube wound at winding angles notheretofore considered possible or contemplated produces completely newand unexpected results in that a spiral tube is provided having strengthcharacteristics heretofore unobtainable in a spiral tube and obtainableonly with a convolutely wound paper tube. This strength increase in thetube of the invention does not require an increase in paper nor in paperstrength but is due primarily to the unusually low tube winding angletogether with the use of paper strips having their fibers oriented so asto approach closely a parallel relationship with the longitudinal axisof a tube wound therefrom. The range of winding angles contemplated bythe invention appear to provide the maximum strength improvement desiredfor spiral tubes, and at the same time are within the practicalconsiderations involved in the manufacture of such tubes.

Not only does the low angle of wind spiral tube of the invention haveimproved strength characteristics but seam splitting common to spiraltubes occurring upon tube failure which is generally injurious tomaterial wound thereon is eliminated and the tube buckles in the natureof a convolute tube. Furthermore, unusually high dimensional stabilityis obtained in the spiral tube of the 5 invention in that changes inmoisture content produce only very small length changes far less thanthose common to spiral tubes Wound at the higher winding anglesconsiderably widening the application for such spiral tubes whereinlength changes must be held to a minimum.

While there has been described what at present is considered to be thepreferred embodiment of the invention, it will be understood by thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention and, therefore, it is theaim of the appended claims to cover all such changes and modificationsas fall within the true spirit and scope of the invention.

Having thus described the invention, what is claimed is:

1. A spirally wound paper tube comprising, a plurality of fibercontaining paper strips spirally wound in overlapping relationship withadhesive therebetween to form a spiral tube, each of said paper stripshaving its fibers lying generally in the direction of the longitudinalaxis of said strips, said strips being wound at a winding angle ofbetween about 15 to 25 degrees thereby providing a dimensionally stabletube of high beam strength and crush strength.

2. A spirally wound paper tube comprising, a plurality of fibercontaining paper strips spirally wound in overlying relationship withadhesive therebetween to form a spiral tube, each of said paper stripshaving its fibers lying generally in the direction of the longitudinalaxis of said strips, said strips being wound at a winding angle ofbetween 17 to 22 degrees thereby providing a dimensionally stable tubeof high beam strength and crush strength.

3. A spirally wound paper tube comprising, a plurality of fibercontaining paper strips spirally wound in over- 4 lying relationshipwith adhesive therebetween to form a spiral tube, each of said paperstrips having its fibers lying generally in the direction of thelongitudinal axis of said strips, said strips being wound at a windingangle of approximately 17 degrees thereby providing a dimensionallystable tube of high beam and crush strength.

References Cited by the Examiner UNITED STATES PATENTS LAVERNE D.GEIGER, Primary Examiner.

LEWIS J. LENNY, Examiner.

1. A SPIRALLY WOUND PAPER TUBE COMPRISING, A PLURALITY OF FIBERCONTAINING PAPER STRIPS SPIRALLY WOUND IN OVERLAPPING RELATIONSHIP WITHADHESIVE THEREBETWEEN TO FORM A SPIRAL TUBE, EACH OF SAID PAPER STRIPSHAVING ITS FIBERS LAYING GENERALLY IN THE DIRECTION OF THE LONGITUDINALAXIS OF SAID STRIPS, SAID STRIPS BEING WOUND AT A WINDING ANGLE OFBETWEEN ABOUT 15 TO 25 DEGREES THEREBY PROVIDING A DIMENSIONALLY STABLETUBE OF HIGH BEAM STRENGTH AND CRUSH STRENGTH.